The present invention relates to an etching apparatus for forming circuit patterns, particularly, microcircuit patterns on a printed circuit board.
A conventional etching apparatus for forming microcircuit patterns on a printed circuit board is carried out by utilizing an etching solvent of water solution including cupric chloride, ferric chloride, persulfate, and hydrogen peroxide, sulfuric acid and alkali solvent or the like, the discharge pressure of the etching solvent from the nozzle is made very low, and with the spraying pressure of the etching solvent is 1.about.3 kg/cm.sup.2.
In the above conventional etching apparatus, the printed circuits are formed with large flow amount of etching liquid, such as low discharge pressure of 1.about.3 kg/cm.sup.2 and discharge flow rate of 8.about.10 lt/min. In this case, the balance of etching becomes uneven on the printed circuit board, resulting in a residue of etching on the upper surface thereof, and an over-etching on the lower surface of the printed circuit board, thereby causing the printed circuits to become loosened from the printed circuit board. Therefore, at present, it is difficult to carry out the stable and uniform etching when forming printed circuits having a width of 0.1 mm or less.